Selects: How Extinction Works

0:00This is an iHeart Podcast. Guaranteed Human Hello friends, it's Josh and I'm back with The Select. And this week I've selected our 2014 episode on extinction. In this episode we go over all the big extinctions and what probably caused them, including the one we're most likely in right now, which is probably caused by humans. And if you pay attention, you can start to notice the little glimmers, the little beginnings of what would become my side podcast, The End of the World with Josh Clark. And although we don't talk about any movies, I'm betting there's some glimmers of Chuck's long-running side podcast, Movie Crush, in here, too.

0:41Hope you enjoy this episode. It's a good one.

0:49Welcome to Stuff You Should Know, a production of iHeartRadio.

0:58Hey, and welcome to the podcast. I'm Josh Clark. There's Charles W. Chuckers Bryant. Jerry is over there. I almost said your last name, Jerry. How weird. And then today we have a fourth character in the studio with this Chuck. This scent. Yeah. Scent. Coming together to make like a tangible human being. So you are wearing patchouli. Not wearing. Well, you have patchouli on you as a result of one of Emily's sugar scrubs, right? Yeah. From Mama? Yeah. And it's loveyourmama.com? Yeah. Okay. And then Jerry is contributing to that with an enchilada. So all of them combined, I would say there's an extra person in this seat right here.

1:44What kind of person is that? Just another person. Okay. A viable living organism. One, that when we leave the studio, we'll probably become extinct That's a good one Did you like that? Yeah, I've had that planned since probably two weeks ago Nice How are you doing, man? I'm good, I've been thinking of Busta Rhymes all day Why? Did he have a song about extinction? He had an album called Extinction Level Event Oh yeah? Yeah, and that was in one of the songs That sounds super 90s Well, it's Busta Rhymes. It has to be 90s. But, I mean, even those words, extinction level event, people were worried about stuff because of, like, the turn of the millennium.

2:29You remember? X-Files was a huge hit. Sure. Deep Impact and Armageddon came out on the same day, basically, and both were hits. Like, people were just nervous. Yeah. And as a result, Busta Rhymes was very popular. That's right, although he's not anymore. He's still good, though. He hasn't been doing much. No, but his body of work is still good. Oh, sure. Yeah. Leaders in the New School. And his early work with Tribe Called Quest. Oh, yeah. He guessed it on one of my favorite songs. Yeah. What's the Scenario? Was that the one? I think so. I mean, he was definitely on that one. Yeah. But that was the one also where I think, yeah, he makes fun of people with saggy pants because it was so new.

3:18Right. Apparently Busta Rhymes wasn't down with it yet. Yeah. Which is pretty ironic because he got hardcore into that. That was raw, raw like a dungeon dragon, right? Right, right. That was pretty awesome. It's a good song. Yeah. So Extinction is clearly what we're talking about today. And I guess we should probably give a shout out to some of the extra reading material. Yeah, man. We picked up on. There's a woman named Elizabeth Colbert, depending on if you watch the Colbert Report. Yeah. She is basically a leading expert, as far as journalists go, on extinction. She wrote a book called The Sixth Extinction.

4:01It's a good article. Yeah, and she wrote an article in The New Yorker. She's a New Yorker journalist that was basically the predecessor to the book. You know how they do? Sure. They're like, oh, I need an extra 20 grand. So I'll just write a synopsis of the book I'm writing. And it's a good article, and we work from that. There's another one from the New York Review of Books called They're Taking Over about the explosion of jellyfish. On How Stuff Works, there's one that I wrote years back called Will We Soon Be Extinct? Yeah. And there's another How Stuff Works one that we've done an episode on called Why Is Biodiversity Important?

4:35Yeah, and I found one in IO9 for animals that we thought were extinct, but miraculously popped back up. Nice. Which is always a good story. Oh, yeah, it's a heartwarming story of triumph over adversity and coming back when everybody thought you were down. Yeah, some of them like... It's basically rocky. Hundreds of millions of years later even. Yeah. It's crazy. Like the silicant? I think that's one. Was that the big fish? Mm-hmm. Yeah. they just caught that thing one day and said, hey, wait a minute. Yeah. This thing's extinct. It's supposed to be. Exactly. We'll talk about how and why things fall off, but things do fall off, and it seems that the whole thing is a very natural process, extinction is.

5:28But for a very long time, I guess scientists believed that God created all of the animals on earth and that his will was too perfect, his creation was too divine to even allow for extinction. So because they were aware of the fossil record, they rationalized these huge bones of animals they didn't see anywhere as we just haven't found them yet. Well, yeah, and this was all the way up into the 19th century, and some really smart people like Thomas Jefferson thought, for instance, when he sent Lewis and Clark out west that they might come across the great Mastodon. Right. He's like, it's bound to be out there somewhere, guys, so be careful.

6:12But there were some other smarter people like George Cuvier in 1812. He was pretty ahead of his time. In fact, in 1812, he was way ahead of his time because he published an essay called Revolutions on the Surface of the Globe. Yeah. And he kind of asserted that, no, things can go extinct. And he called them a species per deus, lost species. Right. And basically hypothesized that there have been cataclysmic events that have caused extinctions. Right. In so many words. This is basically flu in the face of this, that not only was there extinction, but there were huge events that caused it. And so the religious thinkers of the day said, okay, wait, wait, wait, we can work with this.

6:58Because, buddy, what you're talking about is like Noah's flood. So you, my friend, just proved the Bible correct using science. Yeah, Darwin wasn't on board, though. Although he did believe in extinction, he thought the only way it could happen is the gradual extinction. Right. That is also true, and we'll talk about that as well. And, of course, Darwin is this huge hero of biology. So everybody's like, well, Darwin's right about just about everything. So literally until the 1990s, Darwin's view that extinction happens extremely slowly, slower than speciation events. So ultimately, you should always have more species, new species coming up than you have going extinct.

7:42Until the 1990s, that's the way that it was, that's the way it seemed. Yeah. So, Chuck, like I said, all of this stayed around until 1991. Yeah. And it was a result of, like, think about it. Think about how you think of mass extinctions now. You think of an asteroid hitting Earth, destroying everything. And it wasn't until 1991 that that view became widely accepted. And it was because of this dude named Alvarez. He was a geologist, I believe, Walter Alvarez. And in the 70s, he started studying this clay layer that was basically in the fossil record right at the time the dinosaur suddenly died out.

8:24Right. And no one could quite explain what was going on here. They just knew that this must have happened gradually. So it must be a problem with the actual fossil record, not our way of thinking. Yeah, and there are plenty of problems with the fossil record, which we'll get into as well. Right. But Walter Alvarez said, let me look at this in a little more detail. and he looked at the iridium and found that the iridium levels were off the charts, which shouldn't be because it's very, very rare. And we associate iridium on Earth as being brought here by, say, like an asteroid or whatever. Yeah, it's super abundant in asteroids.

8:57So all of a sudden this guy goes, oh, wait a minute. Maybe we can explain this dying out of dinosaurs, where the dinosaurs went 65 million years ago, by an asteroid. And that was in 1980 that they proposed this hypothesis, and they ran into a lot of resistance. And then finally, in 1991, a year after a crater was discovered under the Yucatan Peninsula in Mexico, they dated it and said, yeah, it just so happens that this crater was formed just at the moment the dinosaurs died out. So the Alvarez hypothesis is probably right. And extinction can happen on a mass sudden scale, just as it can also happen on a very long-term scale too.

9:43Yeah, that crater was 112 miles wide, so it fit the profile and basically ended the Cretaceous period in the Mesozoic era. And for a while they called it the Cretaceous Tertiary Event, but now they call it the Cretaceous Paleogene Event. And did you notice that they... Or the KPG. Right. They noticed that... Did you notice the Cretaceous, which is spelled with a C, is denoted with a K. Yeah, it did. Did you see why? It's just German. It's just a German translation for it. I figured it was something like that. Yeah. It was just bugging me. So now, we now believe an asteroid brought us into the Cenozoic era that we enjoy today.

10:25Love the Cenozoic. It's pretty awesome. It's a good era. I mean, it's our era. Yeah. So you gotta love it. You gotta love it. So Chuck, like I said, that extinction can happen, and it does happen, and it's a natural process. If you talk to people about extinction today, though, they say, yeah, we're kind of in a huge extinction event. Yeah, and it makes sense. I mean, when you look at our past, they estimate maybe up to 5 billion species have lived on Earth, and more than 99 % of those are gone. And I love how the New Yorker put it. I think that there's an old joke that all of life on Earth today could be accounted for with a simple rounding error.

11:09Yeah. Like everything we know. So, yeah, we've lost 99 % of things that have ever lived on this planet due to extinction. Right, which again is like it has such a terrible connotation these days, extinction, extinction. But it happens naturally. Apparently, what they've found from looking at the fossil record and from studying life on Earth is that a species tends to have about a 10 million year lifespan. A speciation event occurs where it branches off from one species and produces an entirely new species. And that species, on average, will stick around for about 10 million years. And then something happens and it dies out.

11:50And other species take its place. This is the natural course of life. From what we can tell. The thing is, it normally happens on a very slow time scale. Like when it's what's called background extinction, right? Yeah, the background rate is supposed to be between one and five species per year. But they think that now it could be like a hundred times that. I've seen up to a thousand times the normal rate. And I saw another study from 2014. So it's fresh. And it said that these researchers calculated the normal rates, and they found that there's between 0.023 and 0.135 extinct species per million species per year.

12:37That doesn't really mean much. It means so much that it boggles the mind. Yeah. You know? Like, that's a really strange way of putting it. Yeah, it totally is. But basically, they're saying, like, for every million species on Earth at any given point in time during a year, as low as 0.023 species will die out. So in a year, you shouldn't necessarily have that many species. In current times, though, like you said, between 100 and 1 ,000 times that rate is what we're seeing right now, which is, you could say, alarming. It is alarming. The reason they don't have hard numbers on this stuff is because, like we said, it's a tough thing to study because the fossil record is, well, there's a lot of problems.

13:20One is it's incomplete. We don't really know how many species there have been on Earth since the beginning of Earth. It's just impossible to tell. Fossils form under really specific conditions. So you may think something is gone because it has disappeared from the fossil record. But all that means is there wasn't a fossil. It doesn't necessarily mean it's gone. Right. So that's why things will pop back up. that they'll think, hey, we haven't seen a fossil of this guy in 2 ,000 years, but here it is all of a sudden. And even if it has gone extinct, just where it stopped showing up in the fossil record doesn't mean, like you said, that's when it went extinct right then.

14:01It could have been millions of years later. Well, because then you're supposing that the last thing of that species happened to make a fossil, which is just silly. And also it makes you wonder how many species have lived and died on Earth that just never showed up in the fossil record. Yeah, just weren't fossils at all. Right. Yeah. Well, if it never crawled into amber or, you know, was buried by ash or something, that's luck. Or got trapped in brontosaurus poop. I don't know if that's good luck or bad luck. It's just, it is what it is. It's nature. So because of all these gaps in the fossil record, these researchers that love this topic tend to do a lot of math.

14:41Right. and a lot of speculating with algorithms and mathematical formulas to figure this stuff out. Sure. And that's the only way to do it, really, is to speculate with numbers. It also helps them define things like the minimum viable population, which if you go below that, then it's bad news for the species. It's the minimum amount you can have to still be considered to have a bright future as a thing. Or to just survive as a species, right? Yeah, that's what I mean. Yeah. dim future if you're not surviving. Yeah, math is pretty grim. It can be, in this case, for sure. So we'll talk about exactly what makes an extinction and then what makes up mass extinctions.

15:25But first, let's do a little breakage, huh?

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16:08Okay, so Chuck, you've been talking about animal species going extinct and then showing up again, like the coelacanth. Yeah, or at least disappearing from the record. But we as humans assume they were extinct. Like, again, the coelacanth is this fish that they caught off the coast of South Africa. When did we talk about it? Was it in a This Day in History? I don't remember. We definitely have hit on that, though. I think it was. Because it's huge, right? Yeah, it's a big, ugly fish. Yeah. And it looks like an old dinosaur, but they thought it had died out like 50, 60 million years ago. Actually, way longer.

16:45They thought it disappeared 400 million years ago. Even more impressive. Yeah. So then they caught one off the coast of South Africa in the 30s. Then they caught another one a couple decades later in Madagascar or Mauritius or something. And that made the coelacanth a Lazarus species. Even though it hadn't really gone anywhere, we just thought it did. So we humans having the most important perspective on the entire planet, possibly in the entire universe, it was a Lazarus species to us. Yeah, Lazarus from the Bible. Right. Raised from the dead. Yeah. Like the coelacanth. Again, with the biblical connotations with extinction.

17:23Yeah. There's a lot at stake here. That's true. Another way something might disappear and you might think it's gone is if it actually evolves into a new species. That's called pseudo-extinction. And that's a great success story as well. It is, but it also, I don't understand why that's not just a speciation event. I mean, why is that pseudo-extinction? Why is that any different from regular extinction? Yeah, maybe just because it didn't die out. It actually just changed and evolved. Those are two different things. Yeah, it seems like a gray area to me. Yeah. But for the most part, when an animal just disappears, and we should say, like, even today, we're still finding things that we thought were extinct.

18:08Yeah, yeah. So-called Lazarus species, which goes to make the point, we have no idea how many living species there are on the planet today. Yeah, or have been. It's all just a good guess. It is, using math. Yeah. Grim, grim math. But for the most part, we understand that when a species goes away suddenly, it went extinct. And as we've been saying again and again, extinction is kind of this natural process, or it is a very natural process. And it typically results from a change in the habitat of a species and its inability to adapt. So it dies out. Yeah. Competition with other species, hunting by humans, or perhaps the environment has been tainted by humans.

19:00Humans or a new bacteria or a new virus. The thing is, though, is so these big factors, habitat loss, competition with new species, hunting, and contaminants in the environment, those are the big four reasons that something goes extinct, right? Yeah. Humans can and are responsible for all four of those. Yeah, and this is the extinction that happens over time, obviously. Not a big asteroid hitting the planet. No, but it can happen pretty quickly. And this is a Tracy Wilson joint. And in the introduction, she mentions the Stellar Sea Cow, which was an Arctic resident. It was a big old manatee, basically.

19:40Yeah. And they were first described by Arctic explorers in 1741. By 1768, they were extinct. So it can happen on a pretty rapid scale, especially when you introduce humans. Yeah, and it has a domino effect too because we talked about, and everyone knows about the dangers of losing bees. It's not just like, oh, well, there are no more bees. That's going to affect pollination and plants, and those plants are being fed on by other animals, and it tends to have a snowball effect. like for example the end of the last ice age mammals, small mammals started to go extinct and because of that large animals started to go extinct because they like to eat the small animals.

20:24Exactly, which is the answer to the question why is biodiversity important? Well because ecosystems thrive and survive on a wide number of species that exist pretty much naturally in balance. You know a pretty good example of that stuff falling out of balance is the passenger pigeon. You familiar? Yeah, they're trying to de-extinct that thing. Yeah, you want to talk about de-extinction? Yeah, well, de-extinction is exactly what it sounds like. It is sort of Jurassic Park-y. It is, in 2003, some scientists revived the Bucardo, and that's a Spanish mountain goat, and they did it just sort of like Jurassic Park from DNA that was frozen in time.

21:12Unfortunately, although it did work initially, the DNA only survived a matter of minutes, but it did count as a de-extinction. I think there was a live birth that survived a few minutes, wasn't it? Yeah, the animal itself only survived a few minutes, though. Right. It was like, I should not be. That's true. And, I mean, they basically said it's happening now And we have the capabilities And we may not be able to bring the woolly mammoth back But we might be able to bring back something kind of close Right, and that raises in this article that you sent Just this moral question Like, should we be doing this?

21:55Just because we can, does that mean we should? And so, like, if you bring back an animal That has been extinct for so long That its habitat is now gone Yeah, where are they going to live? Exactly. Where are you going to put it? A zoo? That doesn't seem like a good reason to bring an animal back so we could put it in a zoo. Yeah, and just like maybe this is my opinion here, which we don't do a lot of, but it seems like concentrating on the problems we face now with the extinction rates is something that we should concentrate on, not bringing back the woolly mammoth. Right, and that also kind of dovetails with the point that if we have this ability and routinely exercise it, we may be less inclined to protect the stuff we have now for like, well, if it's important enough, we'll just genetically re-engineer it and bring it back later.

22:42Yeah, I think in the CNN article, they liken it to just thinking we have an undo button on the world. Control Z. Yeah, no good. No. And it's funny because the author doesn't realize that Control-Z works outside of Microsoft Word, too. I'm not sure. He specifically mentioned Control-Z in Microsoft Word. Oh. Word, specifically? Microsoft Word, he said it. Yeah, that's a little weird. He could be a shill, and he was just working it in. Maybe. You know? Well, on Macs, though, it's not Control. Maybe he just meant Microsoft and awkwardly put in Word. Maybe. Or maybe that's the only program he knows.

23:20You know, how do I work this? So you were saying that they're trying to bring back the passenger pigeon, right? Yeah. So the passenger pigeon is this really neat example of what happens when you have a lack of biodiversity. Yeah. There were, when European settlers came to the New World, apparently like one out of every four birds in North America was a passenger pigeon. A quarter of the entire bird population was passenger pigeons. That's a lot of pigeons. That is a ton of pigeons. There are so many that you could just like shoot into like a flock and you would kill a couple hundred. Literally, there were that many.

24:05The thing is, if you read 1493 or 1491, I can't remember which one it is, but both are excellent books by Charles C. Mann. He talks about the passenger pigeon and how they've recently realized that there were so many passenger pigeons because a century before, one of their great predators, the Native American, had been wiped out by disease that had been introduced to the continent about a century before that. So by the time the Europeans got here and really started to settle and encounter the passenger pigeon, they're like, God, look at all these pigeons and didn't realize that the pigeon population had exploded because their natural predator had died off.

24:45Right. And so we, in turn, hunted them into extinction. So because of one near extinction, another species was allowed to thrive and explode. And then that, when they were faced with their predator again, humans, they were eventually wiped out and went extinct. Yeah, the American buffalo, we almost hunted them out of existence. Yeah, or not for Ted Turner. Yeah, we tried our best to. They were just shooting those things for fun at one point. Man, that's disgusting. It is disgusting. You hear about the trains just going through the west and just shooting out the windows at the buffalo for no reason.

25:21Yeah, and doing nothing, just leaving them there to rot. Unbelievable. Remember we did an episode on the buffalo. That was a good one. So sad. No, it was good. Well, it was sad too, though. Oh, gotcha. So if you want to talk about extinction-level events, that's a whole different deal. You want to talk Buster Rhymes. That's not a slow, gradual extinction. That is some big thing that happens that wipes out a lot of living things all at once. They estimate there's been more than 20 of these in the history of the world, but five of them, they call them the big five for a reason. For good reason. We'll just go through those kind of quickly now.

26:04The Ordo-Viscian extinction is about 490 million years ago, and that wiped out about half of all animal families. The reason it wiped out about half was because at the time, most of the stuff on Earth still lived in the sea. Glaciers formed at this time, lowering sea levels, which meant that animals that lived in a certain depth of the sea, usually toward the surface, lost their habitat. Boiled. Yeah. Maybe. Yeah. or were brought down to the level where their predators like to hang out and were eaten en masse. But that accounted for that extinction, which is kind of rare because, as you'll see, when we're talking about the Big Five or mass extinctions in general, it's very difficult to pinpoint exactly what happened.